– STOMACH IS A MUSCULAR BAG LIKE STRUCTURE,STORES FOOD TEMPORARYLY FOR FEW HOURS.

– DIVIDED INTO 3 PARTS i.e FUNDUS,BODY AND PYLORUS.

STRUCTURE

MUCOSA:

FOLDED INTO MANY RUGAE WHICH DISSAPPEAR ON EXPANSION LINED BY SIMPLE COLUMNAR EPITHELIUM.MOST OF IT PROJECTS INTO LAMINA PROPRIA FORMING GASTRIC PITS.GASTRIC PITS ARE SHALLOW.

LAMINA PROPRIA:

RICH IN FUNDIC GLANDS, WHICH CONTAINS

STEM CELLS:

ACTIVE,UNDIFFERENTATED CELLS FOUND AT THE BASE OF LAMINA PROPRIA.

2. ENTERO ENDOCRINE CELLS:

PRESENT ABOVE THE STEM CELLS.ALSO CALLED AS ‘ARGENTAFFIN CELLS’ SINCE THEY ARE STAINED BY SILVER SALTS.BELONG TO APUD (AMINE PRECURSOR UPTAKE DECARBOXYLASE) SYSTEM.

3. CHIEF CELLS/ZYMOGENIC CELLS:

SMALL CUBOIDAL CELLS PRESENT ABOVE ENTEROENDOCRINE CELLS.LARGE IN NUMBER WITH BASOPHILIC CYTOPLASM AND FEW ZYMOGEN GRANULES.

4. OXYNTIC CELLS:

LARGE PYRAMIDAL OR POLYHEDRAL CELLS WITH CENTRAL NUCLEUS.PRESENT IN UPPER HALF OF LAMINA PROPRIA. EASILY IDENTIFIED BY BRIGHT EOSINOPHILIC CYTOPLASM, HENCE THESE ARE CALLED ‘OXYNTIC CELLS’.ALSO CALLED AS ‘PARIETAL CELLS’.SECRETE HCL AND INTRINSIC FACTOR.

5. MUCOUS NECK CELLS:

THESE OPEN INTO GASTRIC PITS AND SECRETE ACID MUCOUS.

MUSCULARIS MUCOSA/INTERNA:

CONSISTS OF INNER CIRCULAR AND OUTER LONGITUDINAL MUSCLE LAYERS.

SUBMUCOSA:

MADE UP OF LOOSE AREOLAR CONNECTIVE TISSUE.MEISSENER’S PLEXUS OF NERVE FIBRES ARE PRESENT.

MUSCULARIS EXTERNA:

CONSISTS OF INNER OBLIQUE,MIDDLE CIRCULAR AND OUTER LONGITUDINAL MUSCLE LAYERS. IN BETWEEN CIRCULAR AND LONGITUDINAL MUSCLE LAYERS, FEW MYENTERIC OR AUERBACH’S PLEXUS OF NERVE FIBRES ARE SEEN.

SEROSA:

OUTER MOST LAYER MADE UP OF FEW CONNECTIVE TISSUE CELLS AND FIBRES, COVERED BY MESOTHELIUM OF VISCERAL PERITONEUM.